Yasiin Bey (formerly known as Mos Def) and Talib Kweli’s reunion as the seminal 90s duo Black Star continued this week, when the duo performed Tuesday night (January 3) on “Late Night With Jimmy Fallon.” In a video from NBC, ?uestlove gives the story behind Black Star’s performance track “Little Brother.” The afro’d drummer insists that the J Dilla-produced song, which samples Roy Ayers “Ain’t Got No Time” is “scientifically, one of the most intricate songs ever crafted.”

?uest explained that Dilla would rework samples that fellow producer Pete Rock used for his own beats, then destroy them out of respect for Rock. Rock once used Ayers’ song “Ain’t Got No Time” as an interlude, but Dilla completely flipped the song. Since the original track featured Ayers talking all over it, Dilla couldn’t use the conventional tactic of looping part of the song, so he chopped 32 snippets of one second or less from the song, and rearranged them into one fluid beat. “He called himself passing time, staying up till four in the morning so he could drive me to the airport,” ?uestlove said, laughing. “…When Matt Damon solved the math problem in “Good Will Hunting,” this was that!”

?uest says that Kweli and Bey stumbled upon the beat on the other side of a beat tape Dilla gave to them, and amazed at how it sounded, they simply rapped over the cassette. The final song ended up on 1999 soundtrack of “The Hurricane,” a film starring Academy Award winner Denzel Washington.

Bey and Kweli’s self-titled album as Black Star garnered critical acclaim with its 1998 release, and fans have clamored for a sequel ever since. The album served as a launchpad for their solo careers, and they continued to collaborate for each others’ albums and for other sporadic projects. In a November interview with MTV Hive Kweli stated that he’d work to get a retail Black Star album out in 2012, and the duo followed through by leaking two new songs together in 2011: “Fix Up” and “You Already Know,” produced by brothers Madlib and Oh No, respectively.

Though Kweli told Vibe magazine weeks after the Hive interview that they would only release the songs as solo leaks, news later surfaced that the duo would release a mixtape that paid tribute to veteran vocalist Aretha Franklin.